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<h1><a name="SECTION006500000000000000000">
4.5 <tt class="module">StringIO</tt> --
         Read and write strings as files</a>
</h1>

<p>
<a name="module-StringIO"></a>

<p>
This module implements a file-like class, <tt class="class">StringIO</tt>,
that reads and writes a string buffer (also known as <em>memory
files</em>).  See the description of file objects for operations (section
<a href="bltin-file-objects.html#bltin-file-objects">3.9</a>).

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><span class="typelabel">class</span>&nbsp;<tt id='l2h-482' xml:id='l2h-482' class="class">StringIO</tt></b>(</nobr></td>
  <td><var></var><big>[</big><var>buffer</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
When a <tt class="class">StringIO</tt> object is created, it can be initialized
to an existing string by passing the string to the constructor.
If no string is given, the <tt class="class">StringIO</tt> will start empty.
In both cases, the initial file position starts at zero.

<p>
The <tt class="class">StringIO</tt> object can accept either Unicode or 8-bit
strings, but mixing the two may take some care.  If both are used,
8-bit strings that cannot be interpreted as 7-bit ASCII (that
use the 8th bit) will cause a <tt class="exception">UnicodeError</tt> to be raised
when <tt class="method">getvalue()</tt> is called.
</dl>

<p>
The following methods of <tt class="class">StringIO</tt> objects require special
mention:

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-483' xml:id='l2h-483' class="method">getvalue</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Retrieve the entire contents of the ``file'' at any time before the
<tt class="class">StringIO</tt> object's <tt class="method">close()</tt> method is called.  See the
note above for information about mixing Unicode and 8-bit strings;
such mixing can cause this method to raise <tt class="exception">UnicodeError</tt>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-484' xml:id='l2h-484' class="method">close</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Free the memory buffer.
</dl>

<p>
Example usage:

<p>
<div class="verbatim"><pre>
import StringIO

output = StringIO.StringIO()
output.write('First line.\n')
print &gt;&gt;output, 'Second line.'

# Retrieve file contents -- this will be
# 'First line.\nSecond line.\n'
contents = output.getvalue()

# Close object and discard memory buffer -- 
# .getvalue() will now raise an exception.
output.close()
</pre></div>

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